ARGUMENT ANALYSIS

Justices throw cold water on Mississippi’s claim to groundwater

The first oral argument of the Supreme Court’s new term, Mississippi v. Tennessee, dealt with Mississippi’s claim that Memphis, Tennessee, is stealing Mississippi’s groundwater. The justices seemed skeptical of Mississippi’s claims — but they also displayed considerable concern about the potential breadth of the “equitable apportionment” doctrine and the court’s potential increasing involvement in future interstate disputes over natural resources.

The justices met in person — with the exception of Justice Brett Kavanaugh, who participated remotely after he tested positive for COVID-19 last week — for the first time since the pandemic struck the country 19 months ago. Questioning was livelier than in online arguments last term, although Justice Samuel Alito was virtually silent.

Arguing for Mississippi, Mississippi Deputy Solicitor General John Coghlan repeatedly emphasized the extraterritorial effect of Memphis’ pumping from an aquifer that straddles the Mississippi-Tennessee border. Coghlan argued that the groundwater extraction created a cone of depression that physically entered into Mississippi. As such, he maintained, Mississippi was suffering from a different type of injury – the invasion of its sovereign territory – than equitable apportionment (the doctrine typically used to resolve surface water disputes) is designed to remedy. He analogized Memphis’ pumping to Tennessee extending a physical pipe into Mississippi to extract its water. David Frederick, representing Tennessee, argued that equitable apportionment was Mississippi’s exclusive remedy, that groundwater pumping in Tennessee had not damaged Mississippi in any way, and that the case should be dismissed. Finally, on behalf of the United States, Frederick Liu, assistant to the U.S. solicitor general, argued that equitable apportionment should apply to interstate groundwater just as it applies to interstate rivers and fish.

The justices were skeptical of Mississippi’s argument, and a common theme throughout their questioning was how to meaningfully limit the rule Mississippi was asking for or distinguish the aquifer pumping from other extraterritorial effects. Justice Clarence Thomas questioned how such a rule could apply to all eight of the states that sit atop the aquifer, with Chief Justice John Roberts noting later that offsetting the multiple extraterritorial effects of groundwater pumping among those states would start to look a lot like equitable apportionment. Justices Elena Kagan and Sonia Sotomayor pressed Coghlan hard to clarify the distinction between the extraterritorial effects from pumping groundwater and extraterritorial effects in surface water cases, with Kagan noting that upstream states create downstream effects by removing lots of water from the river, while Sotomayor asked about an upstream state that dammed a river. Roberts wondered if Tennessee could capture a herd of migrating wild horses while they were in Tennessee and prevent the herd from crossing back into Mississippi. Justice Stephen Breyer posed a fanciful hypothetical about people wanting to take some of San Francisco’s “beautiful fog” back with them to their home states. “What’s the standard when one state takes some of that running-around groundwater that another state says, oh, no, it should stay here?” Breyer asked.  Kavanaugh brought up the eight-state amicus brief to ask how disruptive Mississippi’s rule would be, a point Liu returned to for the United States, arguing that Mississippi’s rule was “unprecedented.”

Nevertheless, the justices also revealed some concern regarding the potential breadth of the equitable apportionment doctrine and their potentially increasing role in interstate disputes over natural resources. Most notably, Sotomayor raised the suggestion from the law professors’ amicus brief that Mississippi might have a cause of action in interstate nuisance, while Kagan grilled the United States about the possibility of an interstate trespass. If the court did rule that equitable apportionment applies to groundwater, Breyer and Justice Neil Gorsuch asked, would that mean that the court has jurisdiction over all groundwater in the country? What about Roberts’ horses and Breyer’s fog? The vision of multiple states suddenly suing each other over groundwater clearly disturbed Breyer.

Justice Amy Coney Barrett asked whether there was something special about groundwater that justified treating it differently, while Kagan, in turn, questioned Tennessee about the possibility that some aquifers might in fact be truly intrastate. Roberts sought clarification of the science, asking whether water in a sandy or silty aquifer truly qualifies as “water” in the same way that water in a river does. Liu offered the “substantial injury” requirement as a filtering device for future equitable apportionment cases, leading to a somewhat confusing discussion with Gorsuch about injury that blended standing and equitable apportionment issues.

A secondary focus of the justices’ questioning was whether, if Mississippi lost, the state should be given leave to amend its complaint to ask for equitable apportionment instead. Sotomayor began this line of questioning, emphasizing that Mississippi has been litigating this issue for 16 years. Gorsuch noted the procedural posture, emphasizing that Mississippi had not filed a motion to amend its complaint, while Kavanaugh sought to clarify that Mississippi wanted to preserve its right to replead. Thomas questioned Frederick about the possibility of Mississippi simply refiling the case. Frederick argued that would require a material change in circumstance — leading Sotomayor to ask what exactly that might be, given that no baseline has yet been established. On further questioning, Frederick said that Mississippi’s complaint based on territorial control should be dismissed with prejudice, which would leave the court free to decide what to do with any future complaint Mississippi filed asking for an equitable apportionment. Kavanaugh posed the prejudice question to the United States, prompting Liu to argue that any amended or new complaint Mississippi filed for an equitable apportionment should be subject to early testing, such as through a motion for judgment on the pleadings.

An interesting theme regarding state sovereignty developed toward the end of oral argument. As Liu correctly noted, equitable apportionment developed as a doctrine to accommodate conflicts between two states’ sovereignty. Mississippi rebutted, however, that Tennessee had unilaterally invaded its sovereignty.

The justices’ eventual opinion in Mississippi v. Tennessee could be one of the shortest the court has ever issued in an interstate water dispute. The court may simply dismiss Mississippi’s territorial claim with prejudice and save the more interesting decisions for the first original jurisdiction complaint that actually seeks equitable apportionment of groundwater. However, if the justices choose to engage the competing visions of state sovereignty vis-à-vis natural resources raised in oral argument, as well as their own concerns about the breadth of the equitable apportionment doctrine and the potential for states to allege other causes of action, the decision in this case could play a substantial role in shaping disputes over interstate natural resources for decades to come.